A professional cook (6)
I believe the answer is:
doctor
I believe this clue is a double definition.
'a professional' is the first definition.
(doctor is a kind of professional)
'cook' is the second definition.
(thesaurus)
(Other definitions for doctor that I've seen before include "Medical specialist" , "Health expert" , "Tamper with - falsify - one of the 14 films" , "Ship's cook" , "An apple a day keeps him away" .)